A robot using a wrist of the aforedescribed type can be used for fitting a male part into a bore, the end of the part and/or the opening of the bore being chamfered so as to facilitate this operation. If the axis of the wrist of the robot coincides perfectly with the axis of the bore, it is sufficient to move the wrist in the direction of this axis for inserting the part into the bore. But, in general, coincidence can only be achieved within the limits of the tolerance of the robot; it may therefore happen that insertion cannot take place. Robot wrists are known which allow a male part to be readily introduced into a bore when the end of the part and/or the opening of the bore are chamfered, and which comprise an arm connected to the robot, an end piece adapted to carry the part, and connecting elements secured to the arm and the end piece which allow free movement of the end piece with respect to the arm and provide self centering of this end piece. Such robots are described more especially in the U.S. Pat. Nos. 4,098,001, 4,337,579, 4,179,783 or in French Pat. No. 2,506,195. But, in these robot wrists, the connection between the arm and the end piece is relatively complicated.
French Pat. No. 1 504 027 further describes a magnetic member formed by two radially magnetized concentric rings separated by an air gap and, on the other hand, a part to be centered which is made from a plastic material and in the mass of which are embedded at least three metal bars or balls. Glass balls may be possibly placed between the member and the part so as to reduce the friction and facilitate centering. For practical reasons this magnetic device cannot be used in known robot wrists.